org.apache.mahout.cf.taste.impl.common.LongPrimitiveArrayIterator.java Source code

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Here is the source code for org.apache.mahout.cf.taste.impl.common.LongPrimitiveArrayIterator.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.mahout.cf.taste.impl.common;

import java.util.NoSuchElementException;

import com.google.common.base.Preconditions;

/**
 * While long[] is an Iterable, it is not an Iterable<Long>. This adapter class addresses that.
 */
public final class LongPrimitiveArrayIterator implements LongPrimitiveIterator {

    private final long[] array;
    private int position;
    private final int max;

    /**
     * <p>
     * Creates an {@link LongPrimitiveArrayIterator} over an entire array.
     * </p>
     * 
     * @param array
     *          array to iterate over
     */
    public LongPrimitiveArrayIterator(long[] array) {
        this.array = Preconditions.checkNotNull(array); // yeah, not going to copy the array here, for performance
        this.position = 0;
        this.max = array.length;
    }

    @Override
    public boolean hasNext() {
        return position < max;
    }

    @Override
    public Long next() {
        return nextLong();
    }

    @Override
    public long nextLong() {
        if (position >= array.length) {
            throw new NoSuchElementException();
        }
        return array[position++];
    }

    @Override
    public long peek() {
        if (position >= array.length) {
            throw new NoSuchElementException();
        }
        return array[position];
    }

    /**
     * @throws UnsupportedOperationException
     */
    @Override
    public void remove() {
        throw new UnsupportedOperationException();
    }

    @Override
    public void skip(int n) {
        if (n > 0) {
            position += n;
        }
    }

    @Override
    public String toString() {
        return "LongPrimitiveArrayIterator";
    }

}